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Open access

Mariusz Specht and Tomasz Szot

Abstract

Producers of GPS receivers nowadays offer many easy-to-use, mobile units for amateur and professional athletes. Similar functionality parameters and a relatively low price make it difficult for the average user to make a choice. This article compares technical aspects of different GPS devices and presents results of their dynamic accuracy evaluation. Selected GNSS units were divided into two groups: specialized dedicated to sports and GPS data loggers. The tests were carried out on the sports stadium of the Gdansk University of Physical Education and Sport, where the lanes were measured with the use of the GPS Total Station phase receivers Leica GS-15 VIVA, supported by Polish Active Geodetic Network ASG-EUPOS. The ellipsoidal coordinates logged in the GNSS sports receivers were transformed in Gauss-Kruger projection to conformal x, y coordinates and statistical distributions of the predictable accuracy were calculated. The article also discusses other (important from a functional point of view) characteristics of GPS receivers used by athletes.

Open access

Cezary Specht, Mateusz Mania, Marcin Skóra and Mariusz Specht

Abstract

A possibility of utilising the GPS system for navigation and transport are fundamentally dependent on the accuracy in positioning. Two fundamental factors decisive for its value are the values of the User Range Error (URE) and Dilution of Precision (DOP), strictly related to the number of satellites forming the constellation. The nominal constellation of GPS satellites consists of 24 units which gives a possibility of identification of coordinates all over the globe. In the last few years, however, the nominal number of satellites in the constellation was much higher, and the URE value has been constantly increasing.

The authors of the paper try to estimate the impact of the changing number of GPS satellites on accuracy of position coordinates with a variable URE value. Mathematical model for estimating geometrical indicators’ value, utilising data derived from the almanac files has been presented. Following a drawn-up algorithm and calculations made with Mathcad software, the authors carried out a comparative analysis of mean daily values of DOP indicators for a variable number of satellites included in the GPS constellation in the years 2001-2013. Then, the authors have established representative values of Two Distance Root Mean Square Error (2drms) 2D and 3D, and calculated a percentage increase of accuracy in the period under discussion.

Open access

Mariusz Specht

Abstract

The DGPS (Differential GPS) and EGNOS (European Geostationary Navigation Overlay Service) systems belong to a group of systems supporting the global satellite system GPS (Global Positioning System). These systems have significantly better navigation performance than GPS and, therefore, they are widely used in the maritime, civil and air navigation. The analysis of the positioning accuracy of GPS leads to the conclusion: from year to year the accuracy of the positioning determination increases. The effect of the permanent increasing of the GPS positioning accuracy is the parallel increasing of the positioning accuracies of all the supporting systems. In connection with the constant improvement of the precision characteristics of the above mentioned systems on one hand and the fact, that the users do not possess the current information about the actual status of these characteristics on the other hand, it is reasonable to conduct the periodical research in this area. For that purpose the long-term measurement campaigns were realized in the years 2006-2014; the values of measures, describing the positioning accuracies obtained by both systems, were determined on the basis of those campaigns.

Open access

Cezary Specht, Emilian Świtalski and Mariusz Specht

Abstract

The accuracy of bathymetric maps, especially in the coastal zone, is very important from the point of view of safety of navigation and transport. Due to the continuous change in shape of the seabed, these maps are fast becoming outdated for precise navigation. Therefore, it is necessary to perform periodical bathymetric measurements to keep them updated on a current basis. At present, none of the institutions in Poland (maritime offices, Hydrographic Office of the Polish Navy) which are responsible for implementation of this type of measurements has at their disposal a hydrographic vessel capable of carrying out measurements for shallow waters (at depths below 1 m). This results in emergence of large areas for which no measurement data have been obtained and, consequently, the maps in the coastal zones are rather unreliable.

The article presents the concept of bathymetric measurements for shallow waters with the use of an autonomous, unmanned survey vessel (ASV/USV). For this purpose, the authors modernized a typical ASV/USV unit with standard radio remote control system to the fully autonomous mode. As part of the modernization, the route planning software was created. The developed software works based on, alternatively, GNSS measurements of the coastline, or satellite images. The system was supplemented by an own autopilot (adapted for flying drones). Moreover, the method of controlling electric motors was changed thanks to the use of own electronic circuit.

The modernized ASV/USV measuring system was verified by performing bathymetric measurements of the retention reservoir in Gdansk, Poland. Then, the obtained measurement data were used to create a digital bottom model and a bathymetric map of the reservoir.